1. Field of the Invention
The present invention relates to a method of measuring a coefficient of dynamic friction between a golf ball and a collisional plate when the golf ball collides with the collisional plate. Analysis of such measurement allows for prediction of a coefficient of dynamic friction at the time of hitting of a golf ball by an actual golf club and can facilitate adjustment of a spin rate of the golf ball.
2. Description of the Background Art
Spin rate of a golf ball is an important characteristic that controls flying distance performance and controllability. A golf ball having high spin rate is able to rapidly stop on the green due to back spin, and is controllable such that its flying path is a draw or a fade by applying side spin to a golf ball. For this reason, golf balls of high spin rate are favored by professional golfers and low-handicapped golfers.
Contrarily, golf balls having low spin rate are inferior in controllability due to their small back spin, however, they are superior in that they can achieve large flying distances. Therefore, they are frequently used by high-handicapped golfers.
Conventionally, spin rate is adjusted by making adjustments on various factors such as rigidity of the entire golf ball, its distribution, degree of rigidity of outermost layer, thickness of outermost layer, distribution of specific gravity of the entire golf ball and the like. For example, U.S. Publication No. 2002/0019268A1 proposes a multilayered golf ball which realizes a larger launch angle and a smaller back spin compared with conventional golf balls.
Meanwhile, in view of golf clubs, depth, width, size, shape, arranging interval of grooves, punch marks or the like formed in a face plane of a club head, as well as surface roughness of the face plane are adjusted. In one known approach, for example, surface roughness or the like of a face plane is changed depending on the club number so that the lower the number of club head, or the relatively smaller the loft angle, the smaller friction coefficient the face plane has, and that the higher the number of club head, the larger friction coefficient the face plane has (see Japanese Patent Laying-Open No. 2004-000675).